Family name Rybchak (Rybchak 
, Рыбчак 
) , all around the world, is a rare cognomen. The family name Rybchak is habitual in Belarus, where it is a rare surname, Russia, and Estonia. Measured by absolute frequency, this name is the most popular in Eastern Europe, particularly Russia, Belarus, and Poland.
| VARIANT | COUNTRY |
|---|---|
| Rybchak | Spain, Poland, Belarus, Canada, Russia |
| Рыбчак | Russia, Kazakhstan, Belarus |